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July 21, 2012
Sand in the Sahara Desert doesn’t always stay put. Tiny particles can be lofted into the air, eventually landing elsewhere in that vast sandy desert. Sometimes dust from the Sahara traverses an entire ocean. That was what happened in July 2012, when a dust plume extended across the Atlantic Ocean toward the Caribbean Sea and Florida.
This color-coded map is made from data collected by the Ozone Mapper Profiler Suite (OMPS) on the SuomiNational Polar-orbiting Partnership (S-NPP) satellite. It shows relative aerosol concentrations across the Atlantic Ocean on July 21, 2012. Lower concentrations appear in yellow, and greater concentrations appear in dark orange-brown. Areas in grey represent data that have been screened out due to sunglint (reflection of sunlight) or other factors.
The dust followed a southward-sweeping arc over the ocean, and remained relatively thick northeast of the Caribbean islands. In the Western Hemisphere, Saharan dust has costs and benefits. Heavy dust transport to the region has coincided with coral declines, yet without regular dustings, some Caribbean islands would be barren rocks devoid of soil. Saharan dust also provides soil to the Amazon Rainforest.
For residents of southern Florida, dust from the Sahara can aggravate breathing difficulties. In July 2012, National Weather Service meteorologists warned that people with respiratory problems should take precautions, but explained that the dust transported across the Atlantic Ocean typically remains 5,000 to 6,000 feet (1,500 to 1,800 meters) above ground. A more likely consequence of the dust would be a “milky or hazy appearance” to southern Florida’s skies.
NASA Earth Observatory image by Jesse Allen, using OMPS research data provided courtesy of Colin Seftor of NASA's Suomi-NPP Ozone Science Team (SSAI). Caption by Michon Scott.
Saharan dust hovered over the Atlantic for several days in mid-January 2008. This image shows two different areas of dust plume activity. Immediately off the coasts of Western Sahara and Mauritania, a series of tan dust plumes blow in predominantly straight lines toward the northwest. Farther west, a large, diffuse plume of dust hangs over the Atlantic Ocean
Floridians looking for a break from hurricane season in late July 2005 were in for a change, though it wasn’t necessarily what they wanted: Saharan dust. By July 19, a massive dust storm had crossed the Atlantic towards southern Florida. This image, captured by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) instrument, shows wide swaths of the planet. On the right is the Sahara Desert, Earth’s biggest dust-producing machine. In the far upper left is North America, this dust storm’s likely target. In the center of the picture, intermixed with clouds, is the swirling dust storm, nearly the size of the United States.